Organic semiconductors have received extensive attention in recent years due to their potential applications for large-area, flexible and ultra low-cost electronics by solution processes. For example, semiconductive polymers like certain polythiophenes, which are useful as active semiconductor materials in thin film transistors (TFTs), have been reported. Nonetheless, many of the semiconductor polythiophenes are not stable when exposed to air as they become oxidatively doped by ambient oxygen. Accordingly, with many of these materials, rigorous precautions have to be undertaken during materials processing and device fabrication to exclude environmental oxygen to avoid or minimize oxidative doping. In addition to low stability when exposed to air, most high-performance organic semiconductors also suffer from poor solution processability.
For example, high-performance polythiophene semiconductors, such as PQT, for electronic device applications such as organic thin film transistors (OTFTs) are not sufficiently soluble in most common organic solvents. Thus, these semiconductors are processed in environmentally undesirable chlorinated solvents such as chlorobenzene or dichlorobenzene for optimal electronic properties. Therefore, it is important to develop new organic semiconductors with both high stability in air and good solution processability in non-chlorinated solvents to allow device fabrications through solution processes, such as spin-coating, dip-coating and ink-jet printing in ambient conditions.